A marathon, or any longer bout of intense exercise, requires fuel to keep you going. It's always been known that you should load up on carbohydrates before a marathon, but the New York Times takes a look at how much, and when you should do it.

In several studies, researchers found that loading up on carbohydrates before a race almost always helps. The trick? Load up the day before. It doesn't matter if you eat a ton of carbs at breakfast or during the race. The New York Times explains:

[S]tatistical analysis showed, those runners, both men and women, who'd eaten the most carbohydrates on the day before the race finished faster than those who'd eaten fewer carbohydrates that day… In both studies, carbohydrates eaten at breakfast on race day, during the race itself or on days earlier in the week were relatively unimportant. It was primarily what people ate on the day before the race that mattered.

So, how many carbohydrates do you need to buff up your marathon time? Get a minimum of six or seven grams for every kilogram of your body weight. That means a 220 pound runner needs at least 700 grams of carbohydrates the day before the race. To do this, replace some of your fats and proteins with carbs. This means juices, rice, pasta, or sweets.